For hundreds of years engineers and scientists have recognized that the ambient thermal energy of the natural environment that is heated by the sun contains essentially unlimited amounts of free thermal energy. Unfortunately, all prior attempts to harness this natural heat energy and convert it into mechanical work by a closed cycle condensing heat engine utilizing this natural thermal energy for its high temperature heat reservoir have failed. As a result of all of these unsuccessful attempts, thermodynamicists have concluded that such engines are impossible. In fact, thermodynamicists are so convinced that such engines are impossible, they have categorically labeled them as "perpetual motion machines of the second kind."
It is important to emphasize, however, that this negative conclusion is not based on any fundamental physical law of nature but rather by the unsuccessful attempts to construct such engines. Although the "second law of thermodynamics" is usually cited as the basic reason why such engines are believed to be imossible, the second law itself is based on unprovable "postulates" laid down by Kelvin, Clausius and Planck over a century ago when the principle of conservation of mass and energy was accepted without question.
The Kelvin-Planck statement of the second law of thermodynamics states that "it is impossible to construct an engine which, operating in a cycle, will produce no other effect than the extraction of heat from a single heat reservoir and the performance of an equivalent amount of work." It is important to emphasize that the word "cycle" in this statement means a closed cycle process wherein the working fluid is circulated over and over again between the heating step and the expansion step such that the thermodynamic state of the working fluid always returns to its initial state. (In fact, strictly speaking, only those devices operating under a closed cycle can be classified as heat engines.) Hence, the second law of thermodynamics only applies to closed cycle heat engines. (See Thermodynamics, Charles E. Merrill Publishing Co., Columbus, Ohio, pages 147-153 by Joachim E. Lay, particularly the footnote at page 148.)
By designing a "heat engine" that falls outside the operating conditions of the second law of thermodynamics it is possible to harness the natural thermal energy of the surrounding environment at ambient temperature and convert a portion of it into useful mechanical work. One such "heat engine" is a simple toy called the "drinking bird" that can be found in almost any novelty shop. Although this engine is a closed cycle condensing heat engine and uses the ambient environment as its high temperature heat reservoir, it operates by generating an artificial low temperature heat reservoir by evaporating water. Hence, it does not operate according to the prescribed conditions of the Kelvin-Planck statement of the second law of thermodynamics and therefore cannot violate this law. The basic thermodynamic operating principles of this engine were analyzed by Carl Bachhuber in his paper, "Energy From the Evaporation Of Water," American Journal of Physics, Vol. 51, No. 3, March 1983, pp. 259-264. In particular, Bachhuber has shown that ordinary water can be used to extract an unlimited amount of natural thermal energy from the surrounding environment and convert it into mechanical work.
Moreover, the specific energy of the water than can be converted into useful mechanical work by this engine is approximately twice the specific energy available in automotive storage batteries. In a technical report issued by the Rand Corporation in August 1966, entitled A Simple Heat Engine of Possible Utility in Primitive Environments, Rand Corporation Publication No. P-3367, Richard Murrow proposed constructing larger versions of this engine for pumping water from the Nile river. A scaled up model of the basic drinking bird engine was constructed to a height of seven feet and found to be able to generate considerable mechanical work. (See, "The Research Frontier--Where is Science Taking Us," Saturday Review, Vol. 50, June 3, 1967, pp. 51-55, by Richard Murrow.) Obviously, engines such as these are not "perpetual motion machines." In principle, larger engines of this type could be used to propel ocean going vessels indefinitely using ordinary sea water for generating an unlimited amount of mechanical work. Although this possibility is generally believed to be thermodynamically impossible, it is clearly not impossible. The existence of these engines proves that it is indeed possible to convert natural heat energy of the environment at ambient temperature into an unlimited amount of mechanical work by creating an artificial low temperature heat reservoir below ambient.
The "atmospheric engine" disclosed herein is a semi-open cycle, multi-stage, heat engine that also converts natural ambient heat energy of the environment into mechanical work but uses ordinary air instead of water to create an artificial low temperature heat reservoir. Since air is universally available all over the Earth, the atmospheric engine will be much more practical than the drinking bird engine. It will be shown that the specific energy of air that can be converted into mechanical work by the atmospheric engine is much higher than the specific energy of water used in the drinking bird engine. Hence, the disclosed atmospheric engine will be much more powerful than the drinking bird engine.
Since the disclosed atmospheric engine is not a closed cycle engine and operates, as in the case of the drinking bird engine, by generating an artificial low temperature heat reservoir below ambient, it does not violate the second law of thermodynamics.